Generally, a vertical split type compressor is structured so as to allow assemblage or removal of a substantially cylindrical bundle accommodating its components, such as a rotor, a blade and the like, into or from a substantially tubular compressor casing (hereinafter, referred to as a “casing”) along an axial direction of the casing (for example, Japanese Unexamined Patent Application, Publication No. H11-270499).
As shown in FIG. 3, the inner circumferential surface of the casing 3′ of a conventional compressor 1′ is provided with a plurality of steps so that the inner diameter becomes smaller toward the tip end portion of the bundle 2′(on the right side in FIG. 3) so as to minimize the clearance between the casing 3′ and bundle 2′ at the deepest insertion position of the bundle 2′. Also, the outer circumferential surface of the bundle 2′ is provided with a plurality of sealing portions 5′ that contact with sealing surfaces (not shown) provided on the inner circumferential surface of the casing 3′ when the bundle 2′ is assembled to the casing 3′, and O-rings 7′ are provided on the outer circumferential surfaces of the sealing portions 5′. Each sealing portion 5′ and each sealing surface contact with each other via the O-ring 7′ in the aforementioned manner to thereby prevent leakage of a compressed material from a gap (not shown) formed between the inner circumferential surface of the casing 3′ and the outer circumferential surface of the bundle 2′.